WO2021100011A1 - Blocs pour freins de roue - Google Patents

Blocs pour freins de roue Download PDF

Info

Publication number
WO2021100011A1
WO2021100011A1 PCT/IB2020/060971 IB2020060971W WO2021100011A1 WO 2021100011 A1 WO2021100011 A1 WO 2021100011A1 IB 2020060971 W IB2020060971 W IB 2020060971W WO 2021100011 A1 WO2021100011 A1 WO 2021100011A1
Authority
WO
WIPO (PCT)
Prior art keywords
block
friction surface
inserts
hardness
wheel brakes
Prior art date
Application number
PCT/IB2020/060971
Other languages
English (en)
Inventor
Vittorio De Soccio
Antonio Ricci
Original Assignee
Cofren S.R.L.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Cofren S.R.L. filed Critical Cofren S.R.L.
Publication of WO2021100011A1 publication Critical patent/WO2021100011A1/fr

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D69/00—Friction linings; Attachment thereof; Selection of coacting friction substances or surfaces
    • F16D69/02—Composition of linings ; Methods of manufacturing
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D65/00—Parts or details
    • F16D65/02—Braking members; Mounting thereof
    • F16D65/04—Bands, shoes or pads; Pivots or supporting members therefor
    • F16D65/092—Bands, shoes or pads; Pivots or supporting members therefor for axially-engaging brakes, e.g. disc brakes
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D69/00—Friction linings; Attachment thereof; Selection of coacting friction substances or surfaces
    • F16D2069/005—Friction linings; Attachment thereof; Selection of coacting friction substances or surfaces having a layered structure

Definitions

  • the invention relates to blocks for wheel brakes featuring better performances under ice or wet conditions.
  • the aforesaid blocks for wheel brakes are usually used in trains with a medium/low speed (a maximum speed of 160 Km/h), with large masses and subjected to frequent braking, such as city trains.
  • the inventors of this invention unexpectedly found out that, if the block comprises inserts made of a material having a heat conductivity which is smaller than that of the material making up the remaining part of the block, the need discussed above can be fulfilled.
  • the subject-matter of the invention is a block for wheel brakes comprising a matrix made of a first material and one or more inserts included inside said matrix and made of a second material having a hardness which is greater than the one of said first material; said one or more inserts being arranged in a symmetrical manner relative to a transverse middle plane; said block being characterized in that said second material has a thermal diffusivity which is lower than that of said first material by at least a value equal to 1*10 -6 m 2 /s than that of said first material; said block having a friction surface made of said first material for 95 to 60% and of said second material for 5 to 40%; said first material being a sintered material.
  • Said second material preferably has a hardness which is greater by at least 20 HRV than that of said first material.
  • the first material preferably has a hardness ranging from 40 to 130 HRV and the second material has a hardness ranging from 80 to 150 HRV.
  • Said first sintered material preferably has a thermal diffusivity ranging from 2.0 to 4.0*10 -6 m 2 /s.
  • Said second material preferably has a thermal diffusivity ranging from 0.5 to 3.0*10 -6 m 2 /s.
  • Said second material preferably is a sintered material.
  • - figures 1 and 2 are a side view and a bottom view, respectively, of a first embodiment of a block for wheel brakes according to the invention
  • FIG. 3 and 4 are a side view and a bottom view, respectively, of a second embodiment of a block for wheel brakes according to the invention
  • figure 5 is a diagram showing the friction coefficients and the temperature changes of the friction surface detected for the block of figure 1 subjected to a plurality of braking operations
  • figure 6 is a diagram showing the friction coefficients and the temperature changes of the friction surface detected for a comparison block subjected to the same plurality of braking operations as in figure 3.
  • number 1 generically indicates, as a whole, a block for wheel brakes according to the invention.
  • the block 1 comprises two side portions 2 made of a sintered material used in the prior art to manufacture the entire block.
  • the block 1 further comprises a central insert 3 made of a material having a hardness, a heat conductivity and a heat capacity which are greater than the ones of the first material making up the side portions 2.
  • Table I shows the physical features of the first material and of the second material.
  • the block 1 comprises a friction surface 4, which is occupied by said first material for 90% and by said second material for 10%.
  • the materials with a different thermal diffusivity and with a different hardness can also be obtained, besides from materials with a different chemical nature, by means of a different process of preparation of a same chemical type of material. For example, thermal diffusivity can be changed by acting upon the porosity of the resulting material.
  • the block 1 described above was subjected to a plurality of braking actions both under dry conditions and under wet conditions. For each one of said braking actions, the temperature change of the friction surface of the block and the block/wheel friction coefficient were measured. The results are shown in the diagram of figure 5.
  • a block entirely made of the sole first sintered material was manufactured as a comparison.
  • the comparison block was subjected to the same braking action to which the block 1 was subjected and, for each one of the braking actions, the temperature of the friction surface and the block/wheel friction coefficient were measured. The results are shown in the diagram of figure 6.
  • a comparison of the two diagrams clearly shows how the temperature changes measured on the friction surface of the block 1 are, on average, 10% greater than the ones measured on the friction surface of the comparison block.
  • This temperature increase translates into a significant friction coefficient increase and, as a consequence, into a more effective braking action.
  • the effect described above is extremely important in the presence of water or ice between the friction surface and the wheel. Indeed, as one can clearly assume, the higher the temperature of the friction surface, the quicker water or ice is removed through evaporation, thus restoring the correct friction between the wheel and the friction surface of the block and, hence, the correct effectiveness of the braking.
  • the inventors of the invention surprisingly found out that the presence, in the block, of inserts made of a material with a greater heat conductivity and capacity ensures a correct efficiency of the braking even in the presence of water or ice. This phenomenon is the result of the significant increase in the temperature of the friction surface, which is caused by the presence of the inserts during the braking phase.
  • This temperature increase can be explained by the ability of the inserts to spread heat to the rest of the friction surface, thanks to the heat conductivity and capacity properties thereof.
  • number 11 indicates, as a whole, a second embodiment of a block according to the invention.
  • the block 11 comprises four portions 12 made of a sintered material used in the prior art to manufacture the entire block and three inserts 13 arranged between the portions 12 and made of a material having a hardness, a heat conductivity and a heat capacity which are greater than the ones of the first material making up the portions 12.
  • the features of the materials making up the portions 12 and the inserts 13 are the same as the ones discussed above for the portions 2 and the inserts 3 of the block 1.
  • the block 11 comprises a friction surface 4, which is occupied by said first material for 90% and by said second material for 10%.
  • the block 11 complies both with the feature concerning the portion of friction surface occupied by said first material and with the symmetry feature, according to which the portions 12 and the inserts 13 have to be arranged in a symmetric position relative to a transverse middle symmetry plane X.
  • the block according to the invention can also assume other configurations, provided that the requirement according to which the relative friction surface consists, for 95 to 60%, of the first material is fulfilled.
  • the solution according to the invention ensures, in general, a block for wheel brakes with a greater friction coefficient and, in particular, offers the great advantage of ensuring the effectiveness of the braking even in the presence of water or ice between the friction surface of the block and the wheel.

Landscapes

  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Braking Arrangements (AREA)

Abstract

L'invention concerne un bloc (1; 11) pour des freins de roue, comprenant une matrice (2; 12) faite d'un premier matériau fritté et un ou de plusieurs éléments rapportés (3; 13) inclus dans la matrice et constitués d'un second matériau ayant une dureté supérieure à celle du premier matériau. Les éléments rapportés sont disposés de manière symétrique par rapport à un plan médian transversal (X). Le second matériau a une diffusivité thermique qui est inférieure d'au moins 1*106 m2/s à celle du premier matériau. Le bloc présente une surface de frottement (4; 14) faite dudit premier matériau pour 95 à 60 % et dudit second matériau pour 5 à 40 %.
PCT/IB2020/060971 2019-11-21 2020-11-20 Blocs pour freins de roue WO2021100011A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT102019000021795A IT201900021795A1 (it) 2019-11-21 2019-11-21 Ceppi per freni su ruota
IT102019000021795 2019-11-21

Publications (1)

Publication Number Publication Date
WO2021100011A1 true WO2021100011A1 (fr) 2021-05-27

Family

ID=69904003

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IB2020/060971 WO2021100011A1 (fr) 2019-11-21 2020-11-20 Blocs pour freins de roue

Country Status (2)

Country Link
IT (1) IT201900021795A1 (fr)
WO (1) WO2021100011A1 (fr)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2219365A (en) * 1988-06-02 1989-12-06 Honda Motor Co Ltd Friction pad for use with disc brake
JP2015165162A (ja) * 2015-03-20 2015-09-17 北海道旅客鉄道株式会社 車両用制輪子及び摩擦材料
US20160047016A1 (en) * 2013-03-25 2016-02-18 Nippon Steel & Sumitomo Metal Corporation Copper alloy powder, sintered copper alloy body, and brake lining for use in high-speed railways

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2219365A (en) * 1988-06-02 1989-12-06 Honda Motor Co Ltd Friction pad for use with disc brake
US20160047016A1 (en) * 2013-03-25 2016-02-18 Nippon Steel & Sumitomo Metal Corporation Copper alloy powder, sintered copper alloy body, and brake lining for use in high-speed railways
JP2015165162A (ja) * 2015-03-20 2015-09-17 北海道旅客鉄道株式会社 車両用制輪子及び摩擦材料

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
DATABASE WPI Week 201564, Derwent World Patents Index; AN 2015-548840, XP002799775 *

Also Published As

Publication number Publication date
IT201900021795A1 (it) 2021-05-21

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